EPIGENETICS, Chaper 2

 

 

With Amanda

 The first grand-child gets the most pictures

 

 

For mid-April this is a spectacularly rotten day, even for Bellingham.  A few minutes ago it was snowing hard; my deck has accumulated a substantial layer of nasty slush.  I know this will seem as nothing to you folks in Kalamazoo and points north and east, but for here it is unusual.  One thing is for sure; the weather has “dampened” my enthusiasm for gardening.  I planted my potatoes, onions and leeks a few days ago, during a four-hour sunny spell.  Now I am hunkered down inside, studying – epigenetics.

I wish Joanne, David, Olivia, Amanda, or anybody else at who is at home in the murky world of biology would ease my pain and explain epigenetics to me, in terms an elderly geologist can comprehend.  If you followed the link in my last blog you may have noticed a link to epigenetics.  Brashly, I clicked on it.  The resulting flood of information promises to keep me inside and out of trouble for a long time.  The  Time link to epigenetics yielded an 8-page article that I can almost understand.  It talks of something called “epigenetic marks”, left mostly unexplained.  Googling that term in turn yielded a Wikipedia article 16 pages long – which cites 138 references!  In despair I just ordered a book on epigenetics, using the Abe Books web site.  It won’t get here for a few weeks, so I have an excuse for sidestepping epigenetics and cancer for a while.  Here is the current state of my ignorance. 

Be warned.  What follows is pure biology, probably misleading, and indubitably boring.  Quit now and enjoy the picture.

“Epigenetics” in this context refers to factors that control gene expression.  Every cell in your body has the same DNA; that is, they all have the blueprint for everything from teeth to toenails to testicles.  Yet you do not grow teeth in your toenails.  This is because these things called epigenetic “marks” control which parts of your DNA – which genes – are “expressed”; that is, used to make proteins.  In your toenail cells the genes to make teeth are turned off by the appropriate epigenetic markers.   Epigenetic markers work biochemically in a number of mind-numbing ways – the most frequently mentioned is “methylation”, which involves plopping a “methyl group” at a crucial spot on the genome.  Apparently this prevents the gene from being expressed.  Epigenetic markers can be influenced by the environment.  To make up an example, if you are starving to death, markers may be manipulated so as to slow down your metabolism and start burning stored fat.  When food becomes available these markers cease to operate and the markers for happy gluttony kick in.  This much I almost understand.  What I cannot fathom is HOW IN HELL CAN THESE THINGS BE INHERITED?   To be Inherited doesn’t a thing have to be coded for in the DNA?  Experiments demonstrate that inheritance does occur –see, for instance, my blog GRANDMAS CURSE.  But how?  I will attack the subject by & by, after the book arrives, but now I’m going to watch the Masters on TV.

The snow has stopped.